The present invention relates to aqueous compositions of acetic acid, and especially to aqueous compositions of acetic acid and at least one of citric acid, malic acid and ascorbic acid, that may be used as insecticides. The compositions may additionally contain minor amounts of surfactant, soap and/or propylene glycol.
Synergistic combinations of acetic and citric acids are known for use as a herbicide, as disclosed in U.S. Pat. Nos. 5,573,997 and 5,705,455. Such compositions consist essentially of acetic acid and citric acid in weight ratios in the range of about 10:1 to about 0.5:1, and with concentrations of acetic acid that are up to about 10 wt. %.
The herbicidal compositions can be formulated to effectively and rapidly kill all vegetative growth, including normally hard-to-kill weeds as well as grasses. Alternatively, the herbicidal compositions may be formulated as a selective herbicide, for example, to kill common lawn weeds, leaving the grass unaffected. The herbicidal compositions may also be used as defoliants.
In contrast, insecticidal compositions are required to paralyze or kill, depending on the particular method of use, insects that infest a plant, without killing the plant. Thus, insecticides are required to have a complete absence of herbicidal activity, or at most only slight herbicidal activity, so that the host plant of the insects is not killed. If any wilting of the plant is observed by the user of the insecticide, then the insecticide will normally be deemed to be unacceptable. Furthermore, it may be important that the insecticide also exhibit properties such that it may be applied to edible material e.g. vegetables, or be capable of being safely applied to vegetation without risk of harm to animals, including humans. Some such insecticidal compositions are known.
An insecticidal composition has now been found that is effective against a variety of insects, with no or minimal herbicidal properties. The insecticidal compositions may be formulated to paralyze insects or to kill them, and moreover may be formulated for effectiveness against several kinds of common insects. In addition, the insecticidal compositions are capable of being applied to edible material and other vegetation without risk of harm to animals, including humans. Furthermore, the insecticidal compositions are friendly to the environment.
An aqueous insecticide composition comprising acetic acid and at least one additional acid selected from the group consisting of citric acid, malic acid and ascorbic acid, the ratio of acetic acid to said at least one acid being in the range of 10:1 to 1:1 on a weight basis, the concentration of acetic acid being less than 8 g/l.
In a preferred embodiment of the invention, the concentration of acetic and citric acids is such that the composition does not exhibit herbicidal properties on tomatoes.
An additional aspect of the invention provides use of aqueous compositions of acetic and at least on of citric acid, malic acid and ascorbic acid, the ratio of acetic acid to said at least one acid being in the range of 10:1 to 1:1 on a weight basis, the concentration of acetic acid being less than 8 g/l as an insecticide, especially such use in the absence of herbicidal activity.
A further aspect relates to a method of treatment of insects with an insecticide comprising, spraying the insects with an aqueous insecticide composition comprising acetic acid and at least one of citric acid, malic acid and ascorbic acid, the ratio of acetic acid to said at least one acid being in the range of 10:1 to 1:1 on a weight basis, the concentration of acetic acid being less than 8 g/l.
Further aspects of the invention are as follows:
An aqueous insecticide composition comprising acetic acid in a concentration up to 50 g/l and surfactant.
An aqueous insecticide composition comprising citric acid in concentration up to 25 g/l and surfactant.
An aqueous insecticide composition comprising an insecticidal effective amount of a surfactant, especially Sponto(trademark) 300T surfactant.
The present invention relates to aqueous insecticidal compositions of acetic acid, especially aqueous insecticidal compositions of acetic acid and at least one of citric acid, malic and ascorbic acid. However, the invention will be particularly described herein with reference to a preferred embodiment viz. aqueous insecticidal compositions of acetic acid and citric acid.
The combination of acetic and citric acids exhibits synergistic effects as an insecticide, with the resulting composition being more effective as an insecticide than a corresponding composition of acetic acid or citric acid alone at the same concentration. In addition, the insecticidal composition may be formulated such that the concentration of acetic and citric acids is such that the composition does not exhibit herbicidal properties, especially herbicidal properties with respect to tomatoes, cabbage, roses and peppers, broad leaf plants and/or other vegetation.
In embodiments, the composition of the invention comprises a synergistic combination of acetic acid and citric acid, in aqueous solution. The acetic acid component is conveniently provided by domestic white vinegar while the citric acid is conveniently provided by lemon juice or juices of other citrus fruits. It is understood, however, that industrial sources of either or both of these components may be used. For instance, the composition may be formulated using glacial acetic acid.
The weight ratio of acetic acid to citric acid in the insecticidal composition may vary over a wide range, for instance, in the range of from about 10:1 to about 1:1, preferably in the range of 4:1 to 1:1, on a weight basis.
In embodiments, the weight ratio of acetic acid to citric acid is in the range of 4:1 to about 2:1.
The insecticidal composition in use may contain up to 100 g/l of acetic acid and 50 g/l of citric acid, with the preferred amount of acetic acid being up to 10 g/l and especially up to 4 g/l.
The composition should contain at least 1 g/l of acetic acid and 0.5 g/l of citric acid. Preferred compositions contain about 4 g/l of acetic acid and 2 g/l of citric acid.
The insecticidal activity of the combination of acetic acid and citric acid may be enhanced by addition of surfactants, vegetable oils, alkylene glycol and/or soap. Although soap is known for use in insecticidal compositions, the amount of soap added to the compositions of the present invention is less than that normally used for insecticidal compositions in which soap is the active ingredient.
It is believed that a wide variety of surfactants may be used.
Examples of alkylene glycols include propylene glycol.
Examples of soaps include insecticidal soaps.
A particularly preferred composition contains acetic acid, citric acid and surfactant, especially a surfactant available as Sponto(trademark) 300T. Other surfactants may be used. The amount of surfactant should be in the range of 0.1-40 g/l, preferably 1-5 g/l.
In another embodiment of the invention, the citric acid may be replaced in whole or in part with malic acid and/or ascorbic acid. Thus, the composition may be acetic acid with one or more acids selected from the group consisting of citric acid, malic acid and ascorbic acid. Concentration and ratios of the acetic acid and other acid have been discussed above with respect to use of citric acid.
In further embodiments, acetic acid may be used with surfactant as an insecticide, with or without added citric or other acid.
In still further embodiments, citric acid may be used with surfactant as an insecticide, with or without added acetic or other acid.
The insecticidal composition may be formulated so as to be effective on one or more of a variety of insects. In addition, the insecticidal composition may be formulated so as to kill the insects or to merely paralyze the insects. In the latter instance, it might be beneficial to be able to spray vegetation e.g. a house plant, so as to paralyze the insects which are then removed from the location of the house plant. Such use could be beneficial if higher concentrations of the insecticide might be harmful to the plant.
It is believed that surfactants, soaps and propylene glycol aid in effecting penetration of the composition of acetic and citric acids into the insect, to increase its effectiveness. Thus, surfactants, soaps and propylene glycol tend to increase the toxicity of the acids. However, the increase in toxicity may be dependent on the insect, and the examples herein show instances of adverse or antagonistic effects. For example, addition of surfactant and soap had antagonistic effects in the effectiveness of acetic acid and citric acid on flea beetles but not on corn root worm.
In the examples below, unless indicated to the contrary, individual insects were counted and placed in a clean glass beaker, where they were sprayed with the insecticidal composition being tested. The insects were then immediately transferred to a clean, dry glass flask and covered with paper tissue. The insects remained in the latter flasks for a period of 24 hours, at which time the insects were inspected.
The insecticidal compositions being tested were formulated in aqueous solution. The amounts of the ingredients are specified in the examples, and unless stated otherwise, are expressed in grams/litre.